Use of a fuel composition comprising three additives for cleaning the internal parts of petrol engines

ABSTRACT

The present invention relates to the use, for reducing deposits in the internal parts of a spark ignition engine, of a fuel composition comprising at least three additives: a quaternary ammonium salt, a non-quaternary polyisobutylene succinimide and a Mannich base which is different from the other additives. The composition is such that the mass ratio of the quantity of the first additive to the quantity of the second additive is in the range from 0.2:1 to 2.5:1.

The present invention relates to the use, for reducing and/or preventing deposits in the internal parts of a spark ignition engine, of a fuel composition which comprises at least three additives: a quaternary ammonium salt, a non-quaternary polyisobutylene succinimide, and a Mannich base, different from the other two additives. The composition is such that the mass ratio of the amount of the first additive to the amount of the second additive is in the range from 0.2:1 to 2.5:1.

The invention also relates to the use, to improve detergency properties of a gasoline fuel, of a fuel concentrate comprising at least said three additives, in mixture with an organic liquid inert to said additives.

The composition is also used to keep clean (keep-clean effect) and/or to clean up (clean-up effect) deposits in the engine, as well as to reduce fuel consumption of the engine (“Fuel Eco” action) and/or to minimise power loss of said engine, and/or to reduce emissions of pollutants, in particular, particulate emissions from the combustion engine, and/or to reduce fouling of the pistons of the engine, preferably in gasoline direct injection (or GDI).

PRIOR ART

Liquid fuels for internal combustion engines contain components that can degrade during engine operation. The problem of deposits in the internal parts of combustion engines is well known to engine manufacturers. It has been shown that the formation of these deposits has consequences for engine performance and especially has a negative impact on fuel consumption and particulate emissions (Gueit, J. et al, “Injector Fouling in Direct Injection Spark Ignition Engines—A New Test Procedure for the Evaluation of Gasoline Additives,” SAE Technical Paper 2017-01-2294). Advances in fuel additive technology made it possible to address this problem. So-called detergent additives used in fuels have already been provided to keep clean (“keep-clean” effect) the engine by limiting deposits or by reducing deposits already present in the internal parts of the combustion engine (“clean-up” effect). Mention can be made by way of example of document U.S. Pat. No. 4,171,959, which describes a detergent additive for gasoline fuel containing a quaternary ammonium function.

However, engine technology is constantly changing over time and fuel requirements have to change to cope with these technological advances in combustion engines.

In particular, new gasoline direct injection systems expose injectors to more severe pressure and temperature conditions which favour the formation of deposits.

Furthermore, these new injection systems have more complex geometries to optimise spraying, especially more holes with smaller diameters, but which, on the other hand, lead to a greater sensitivity to deposits. The presence of deposits can affect combustion performance, especially in terms of increased pollutant emissions and particulate emissions.

Other consequences of excessive deposits have been reported in the literature, such as increased fuel consumption, and hence particulate emissions, and driveability problems.

The prevention and reduction of deposits in these new engines is essential for the optimal operation of today's engines. There is therefore a need to provide detergent fuel additives that promote optimum performance of combustion engines, especially for new engine technologies but also for older/conventional engine technologies.

In the case of spark ignition engines (or gasoline engines) with indirect injection, a particular problem arises due to the formation of deposits on the external parts of the engine and especially on the intake valve stems for the air/fuel mixture upstream of the combustion chamber, which results in a phenomenon of valve sticking.

This phenomenon, well known to those skilled in the art as “valve sticking”, is described in a reference publication by Seppo Mikkonen, Reino Karlsson and Jouni Kivi entitled “Intake Valve Stiking in Some Carburetor Engines”, SAE Technical Paper Series n° 881643, International Fuels and Lubricants Meeting and Exposition, Portland, Oreg., Oct. 10-13, 1988.

This phenomenon is caused by the accumulation of high viscosity deposits at the interface between the intake valve stem and the valve guide in indirect injection spark ignition engines during low temperature engine operation (e.g. in cold weather). The accumulation of such deposits on the valve stems hinders valve movements, the stems stick to the valve guides, which causes poor valve closure, generates sealing problems in the combustion chamber, and can significantly affect engine operation, and in particular may prevent starting in cold weather.

In general, there are different types of deposits on the intake valves of indirect injection spark ignition engines. These types of deposits are well known to engine manufacturers, and the appearance of some of them is dependent on treatment solutions for others.

On the one hand, a first type of deposit consists of those which form at high temperature on the intake valves of indirect injection spark ignition engines when employing a fuel containing no detergent additive. These deposits especially consist of carbon residues related to the coking phenomenon and can also include deposits of the soap and/or lacquer type (“lacquering”). These deposits are generally treated by the use of detergent additives added to the fuel (additivated fuel).

On the other hand, a second type of deposit consists of the aforementioned viscous deposits which form at low temperature and appear on the intake valves of indirect injection spark ignition engines when using additivated fuels, thus causing the valve sticking phenomenon described hereinabove.

Thus, the additivation of fuel for the treatment and prevention of deposits that form at high temperatures can cause viscous deposits to appear at low temperatures.

As set out in the above-mentioned publication (SAE Technical Paper Series No. 881643), the composition of gasoline and the additives it contains have a highly important influence on valve sticking phenomena. In particular, detergent additives conventionally incorporated into gasolines to keep the valves clean have paradoxically proved to promote valve sticking. In a known manner per se, the problem of valve sticking does not occur or occurs only to a very limited extent when a fuel free of detergent additives is employed. Furthermore, the above-mentioned publication shows that polymeric-type additives, likely to be used in gasolines and/or engine oils, are known to be valve sticking promoters.

W02006135881 describes a detergent additive containing a quaternary ammonium salt used to reduce or clean deposits especially on intake valves.

Solutions provided in prior art are not fully satisfactory. There is therefore a need to provide fuel additives that promote optimal performance of spark ignition engines and are effective in preventing all types of deposits, including on intake valves.

There is also a need for a general purpose detergent additive capable of acting on deposits regardless of engine technology (direct or indirect injection) and/or fuel properties, while minimising the treatment rate i.e. the amounts of additive(s) employed.

OBJECT OF THE INVENTION

The applicant has discovered that the use of a fuel composition comprising at least three additives, as described hereafter, has remarkable and unexpected detergency properties for internal combustion engines, preferably gasoline engines, known as spark ignition engines. This combination of additives makes it possible to ensure and improve detergency of fuels intended for use in internal combustion engines. It also yields an unexpected synergistic effect.

Additional advantages of the fuel additive composition used according to the invention are:

-   -   protection of pumps, injection systems, piston zone, rings,         liners and all moving parts with which this additive comes into         contact in an engine,     -   optimal engine operation,     -   reduced fuel consumption,     -   savings due to less engine maintenance and lower fuel         consumption,     -   reduced particulate emissions,     -   efficiency in gasoline direct injection and indirect injection.

One object of the present invention is thus the use, for reducing and/or preventing deposits in the internal parts of a spark ignition engine, of a fuel composition comprising:

(1) at least one first additive consisting of a quaternary ammonium salt,

(2) at least one second additive consisting of a non-quaternary polyisobutylene succinimide,

(3) at least one third additive, different from additives (1) and (2), consisting of a Mannich base, and

wherein the mass ratio of the amount of the first additive to the amount of the second additive is in the range from 0.2:1 to 2.5:1.

Preferably, the mass ratio of the amount of the first additive to the amount of the second additive in the composition is in the range from 1:1 to 2:1, and preferably from 1.25:1 to 1.5:1.

Another object of the invention is also a use of the composition, to keep clean (keep-clean effect) and/or clean up (clean-up effect) deposits in the internal parts of a spark ignition engine, selected from the following: the combustion chamber and the fuel injection system, and preferably the fuel injection system.

A further object of the invention is a use, to improve detergency properties of a gasoline fuel, of a fuel concentrate comprising at least the three additives hereinabove, in mixture with an organic liquid, said organic liquid being inert with respect to the first, second and third additive, and miscible with said fuel.

The invention also relates to a process for keeping clean and/or cleaning up at least one of the internal parts of a spark ignition engine (or internal combustion gasoline engine), comprising at least the following steps:

-   -   preparing a fuel composition by additivating a fuel with at         least the three additives defined hereinabove, or a concentrate         comprising them, then     -   combusting said fuel composition in said spark ignition engine.

Further objects, characteristics, aspects and advantages of the invention will become even more apparent upon reading the following description.

In the following, and unless otherwise indicated, the bounds of a range of values are included in that range, especially in the expressions “between” and “ranging/ranges from . . . to . . . ”.

Furthermore, the expressions “at least one” and “at least” used in the present description are respectively equivalent to the expressions “one or more” and “greater than or equal to”.

Finally, in a manner known per se, a C_(N) compound or group is a compound or group containing N carbon atoms in its chemical structure.

DETAILED DESCRIPTION The First Additive: Quaternary Ammonium

The composition according to the invention comprises a first additive consisting of a quaternary ammonium salt obtained, in a first embodiment, by reaction with a quaternisation agent of a nitrogen compound comprising a tertiary amine function, this nitrogen compound being the product of the reaction of an acylation agent substituted with a hydrocarbon group and of a compound comprising at least one tertiary amine group and at least one group selected from primary amines, secondary amines and alcohols.

In a second embodiment, the quaternary ammonium salt is selected from quaternised PIBA (polyisobutylene amine) compounds, or from quaternised polyether amines.

According to the first and preferred embodiment, said nitrogen compound is the reaction product of a hydrocarbon-substituted acylating agent and a compound comprising both an oxygen atom or a nitrogen atom capable of condensing with said acylating agent (i.e. this compound comprises at least one group selected from primary amines, secondary amines and alcohols) and a tertiary amine group.

The acylating agent is advantageously selected from mono- or poly-carboxylic acids and derivatives thereof, especially their ester, amide or anhydride derivatives. The acylating agent is preferably selected from succinic, phthalic and propionic acids and the corresponding anhydrides.

In this embodiment, the acylating agent is substituted with a hydrocarbon group. By “hydrocarbon” group, it is meant any group having a carbon atom directly attached to the rest of the molecule (i.e. to the acylating agent) and having predominantly an aliphatic hydrocarbon character.

Hydrocarbon groups according to the invention may also contain non-hydrocarbon groups. For example, they may contain up to one non-hydrocarbon group per ten carbon atoms provided that the non-hydrocarbon group does not significantly alter the predominantly hydrocarbon character of the group. Examples of such groups well known to the skilled person are hydroxyl groups, halogens (in particular chloro- and fluoro-groups), alkoxy, alkylmercapto and alkylsulphoxy groups.

In one embodiment, preferably the hydrocarbon substituents do not contain such non-hydrocarbon groups and are purely aliphatic hydrocarbons.

The hydrocarbon substituent of the acylating agent preferably comprises at least 8, preferably at least 12 carbon atoms. Said hydrocarbon substituent may comprise up to about 200 carbon atoms.

The hydrocarbon substituent of the acylating agent preferably has a number average molecular mass (Mn) of from 160 to 2800, for example from 250 to 2000, more preferably from 500 to 1500 and even more preferably from 500 to 1300. A range of Mn values between 700 and 1300 is particularly preferred, for example from 700 to 1200.

Examples of hydrocarbon substituent groups for the acylating agent include n-octyl, n-decyl, n-dodecyl, tetrapropenyl, n-octadecyl, oleyl, octadecyl or triacontyl groups.

The hydrocarbon substituent of the acylating agent may also be obtained from homo- or inter-polymers (e.g. copolymers, terpolymers) of mono- and di-olefins having 2 to 10 carbon atoms, for example from ethylene, propylene, 1-butene, isobutene, butadiene, isoprene, 1-hexene or 1-octene. Preferably, these olefins are 1-mono-olefins.

The hydrocarbon substituent of the acylating agent may also be selected from derivatives of halogenated (e.g. chlorinated or brominated) analogues of these homo- or inter-polymers.

According to one alternative, the hydrocarbon substituent of the acylating agent may be obtained from other sources, for example from high molecular weight alkene monomers (e.g. 1-tetracontene) and their chlorinated or hydrochlorinated analogues, aliphatic petroleum fractions, e.g. paraffin waxes, their cracked, chlorinated and/or hydrochlorinated analogues, white oils, synthetic alkenes, e.g. produced by the Ziegler-Natta process (e.g. polyethylene fats) and other sources known to the skilled person.

Any unsaturation present in the hydrocarbon group of the acylating agent may optionally be reduced or removed by hydrogenation according to any known process.

The hydrocarbon substituent of the acylating agent is preferably essentially saturated, i.e. it contains no more than one unsaturated carbon-carbon bond for every ten carbon-carbon single bonds present.

The hydrocarbon substituent of the acylating agent advantageously contains no more than one non-aromatic carbon-carbon unsaturated bond for every 50 carbon-carbon bonds present.

According to one preferred embodiment, the hydrocarbon substituent of the acylating agent is a polyisobutene group also known as polyisobutylene (PIB). In particular, so-called highly reactive polyisobutenes (PIBs) are preferred. Highly reactive polyisobutenes (PIBs) are understood to be polyisobutenes (PIBs) in which at least 50 mole %, preferably at least 70 mole % or more, of the end olefinic double bonds are of the vinylidene type as described in document EP0565285. In particular, preferred PIBs are those having more than 80 mole % and up to 100 mole % vinylidene end groups as described in document EP1344785.

According to one particularly preferred embodiment, the hydrocarbon-substituted acylating agent is a polyisobutenyl succinic anhydride (PIBSA).

The preparation of polyisobutenyl succinic anhydrides is known per se, and widely described in the literature. There can be mentioned by way of example the processes comprising the reaction between polyisobutenes (PIBs) and maleic anhydride described in documents U.S. Pat. Nos. 3,361,673 and 3,018,250 or the process comprising the reaction of a halogenated, in particular chlorinated, polyisobutene (PM) with maleic anhydride (U.S. Pat. No. 3,172,892).

According to one alternative, polyisobutenyl succinic anhydride can be prepared by mixing a polyolefin with maleic anhydride and then passing chlorine through the mixture (GB949981).

Other hydrocarbon groups comprising an internal olefin, for example as described in application W02007/015080, may also be used as a substituent for the acylating agent. By internal olefin, it is meant any olefin containing predominantly a non-alpha double bond, which is a beta- or higher-position olefin.

Preferably, these materials are essentially beta-olefins or higher-position olefins, for example containing less than 10% by weight of alpha-olefin, advantageously less than 5% by mass or less than 2% by mass.

The internal olefins can be prepared by isomerisation of alpha-olefins according to any known process.

The compound comprising both an oxygen atom or a nitrogen atom capable of condensing with the acylating agent and a tertiary amine group may, for example, be selected from the group consisting of: dimethylaminopropylamine, N,N-diethylaminopropylamine, N,N-dimethylamino-ethylamine, N,N-dimethyl-amino ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, butylenediamines (isomers), diethylenetriamine, dipropylenetriamine dibutylenetriamine, triethylenetetraamine, teraethylenepentaamine, pentaethylenehexaamine, hexamethylenetetramine, bis(hexamethylene) triamine, diaminobenzenes, and pentanediamines, hexanediamines, heptanediamines, and preferably N,N-dimethylaminopropylamine.

Said compound may further be selected from alkylamine-substituted heterocyclic compounds such as 1-(3-aminopropyl)-imidazole, 4-(3-aminopropyl)morpholine, 1-(2-aminoethyl)piperidine, 3,3-diamino-N-methyldipropylamine, diaminopyridines, and 3,3-bisamino(N,N-dimethylpropylamine).

The compound comprising both an oxygen atom or a nitrogen atom capable of condensing with the acylating agent and a tertiary amine group may also be selected from alkanolamines, including, but not limited to, triethanolamine, trimethanolamine, N,N-dimethylaminopropanol, N,N-dimethylaminoethanol, N,N-diethylaminopropanol, N,N-diethylaminoethanol, N,N-diethylaminobutanol, N,N,N-tris(hydroxyethyl)amine, N,N,N-tris(hydroxymethyl)amine, N,N,N-tris(aminoethyl)amine, N,N-dibutylaminopropylamine and N,N,N′-trimethyl-N′-hydroxyethyl-bisaminoethylether, N,N-bis(3-dimethylamino-propyl)-N-isopropanolamine, N-(3-dimethylamino-propyl)-N,N-diisopropanolamine, N′-(3-(Dimethylamino)propyl)-N,N-dimethyl-1,3-propanediamine 2-(2-dimethylaminoethoxy)ethanol and N,N,N′-trimethylaminoethylethanolamine, or mixtures thereof.

According to one preferred embodiment, said compound comprising at least one tertiary amine group and at least one group selected from primary amines, secondary amines and alcohols is selected from amines of following formula (I) or (II):

wherein:

R6 and R7 are identical or different and represent, independently of each other, an alkyl group having from 1 to 22 carbon atoms, preferably having from 1 to 5 carbon atoms;

X is an alkylene group having from 1 to 20 carbon atoms, preferably from 1 to 5 carbon atoms;

m is an integer between 1 and 5;

n is an integer from 0 to 20; and

R8 is a hydrogen atom or a C1-C22 alkyl group.

Said compound is preferably selected from amines of the formula (I).

When the nitrogen compound comprises an amine of formula (I), R8 is advantageously a hydrogen atom or a C1-C16 alkyl group, preferably a C1-C10 alkyl group, even more preferably a C1-C6 alkyl group.

R8 may, for example, be selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl and isomers thereof. Preferably R8 is a hydrogen atom.

When the nitrogen compound comprises an amine of formula (II), m is preferably equal to 2 or 3, more preferably equal to 2; n is preferably an integer between 0 and 15, more preferably between 0 and 10, even more preferably between 0 and 5. Advantageously, n is 0.

According to one preferred embodiment, said nitrogen compound is the reaction product of the acylating agent substituted with a hydrocarbon group and a diamine of the formula (I).

In this embodiment, preferably:

-   -   R6 and R7 represent, independently of each other, a C1-C16 alkyl         group, preferably a C1-C10 alkyl group;     -   R6 and R7 represent, independently of each other, a methyl,         ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl group or         isomers thereof. Advantageously, R6 and R7 represent,         independently of each other, a C1-C4 group, preferably a methyl         group;     -   X represents an alkylene group having 1 to 16 carbon atoms,         preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon         atoms, for example 2 to 6 carbon atoms or 2 to 5 carbon atoms. X         particularly preferably represents an ethylene, propylene or         butylene group, in particular a propylene group.

According to one particularly preferred embodiment, the nitrogen compound is the reaction product of a succinic acid derivative substituted with a hydrocarbon group, preferably a polyisobutenyl succinic anhydride, and an alcohol or an amine also including a tertiary amine group, especially a compound of formula (I) or (II) as described hereinabove and more preferably a compound of formula (I).

According to first alternative, the succinic acid derivative substituted with a hydrocarbon group reacts with the amine also comprising a tertiary amine group under such conditions to form a succinimide (closed form). The reaction of the succinic acid derivative and the amine may also result under certain conditions in a succinamide, i.e. a compound comprising an amide group and a carboxylic acid group (open form).

According to a second alternative, an alcohol also comprising a tertiary amine group reacts with the succinic acid derivative to form an ester also comprising a free carboxyl group —CO₂H (open form). Thus, in some embodiments the nitrogen compound may be the reaction product of a succinic acid derivative and an amine or alcohol which is an ester or amide and which further also comprises an unreacted carboxyl group —CO₂H (open form).

The quaternary ammonium salt forming the first additive according to the present invention is directly obtained by reaction between the above described nitrogen compound comprising a tertiary amine function and a quaternising agent.

According to one particular embodiment, the quaternising agent is selected from the group consisting of dialkyl sulphates, carboxylic acid esters, alkyl halides, benzyl halides, hydrocarbon carbonates, and hydrocarbon epoxides optionally in mixture with an acid, alone or in mixture, preferably carboxylic acid esters.

In fuel compositions, it is often desirable to reduce content of halogen, sulphur and compounds containing phosphorus.

Thus, if a quaternising agent containing such an element is used, it may be advantageous to carry out a subsequent reaction to exchange the counterion. For example, a quaternary ammonium salt formed by reaction with an alkyl halide may then be reacted with sodium hydroxide and the sodium halide salt filtered off.

The quaternising agent may include halides such as chloride, iodide or bromide; hydroxides; sulphonates; bisulphites; alkyl sulphates such as dimethyl sulphate; sulphones; phosphates; C1-C12 alkylphosphates; C1-C12 dialkylphosphates; borates; C1-C12 alkylborates; nitrites; nitrates; carbonates; bicarbonates; alkanoates; O,O-dialkyldithiophosphates, alone or in mixture.

According to one particular embodiment, the quaternising agent may be selected from dialkyl sulphate derivatives such as dimethyl sulphate, N-oxides, sulphones such as propane- and butane-sulphone, alkyl, acyl or aralkyl halides such as methyl and ethyl chloride, benzyl bromide, iodide or chloride, and hydrocarbon carbonates (or alkylcarbonates).

If the acyl halide is benzyl chloride, the aromatic ring is optionally substituted with one or more alkyl or alkenyl groups.

The hydrocarbon (alkyl) groups of the hydrocarbon carbonates may contain from 1 to 50, 1 to 20, 1 to 10 or 1 to 5 carbon atoms per group. According to one embodiment, the hydrocarbon carbonates contain two hydrocarbon groups which may be the same or different. Examples of hydrocarbon carbonates include dimethyl or diethyl carbonate.

According to one preferred embodiment, the quaternising agent is selected from hydrocarbon epoxides represented by the following formula (III):

wherein R9, R10, R11 and R12 may be the same or different and independently represent a hydrogen atom or a C₁-C₅₀ hydrocarbon group. By way of non-limiting examples, there can be mentioned styrene oxide, ethylene oxide, propylene oxide, butylene oxide, stilbene oxide and C₁C₅₀ epoxides. Styrene oxide and propylene oxide are particularly preferred, and more preferably the quaternising agent is propylene oxide.

Such hydrocarbon epoxides can be used as quaternising agent in combination with an acid, for example with acetic acid. Hydrocarbon epoxides can also be used alone as a quaternising agent, especially without additional acid.

Without being bound by this assumption, it would appear that the presence of the carboxylic acid function in the molecule promotes formation of the quaternary ammonium salt. In one such embodiment not using additional acid, a protic solvent is used for the preparation of the quaternary ammonium salt. By way of example, protic solvents such as water, alcohols (including polyhydric alcohols) may be used alone or in mixture. Preferred protic solvents have a dielectric constant greater than 9.

Corresponding quaternary ammonium salts prepared from amides or esters and succinic acid derivatives are described in W02010/132259 or in EP1896555.

According to another embodiment, the quaternising agent is selected from compounds of the formula (IV):

wherein R13 is an optionally substituted alkyl, alkenyl, aryl and aralkyl group, and R14 is a C₁ to C₂₂ alkyl, aryl or alkylaryl group.

The compound of the formula (IV) is a carboxylic acid ester capable of reacting with a tertiary amine to form a quaternary ammonium salt. Compounds of the formula (IV) are selected, for example, from carboxylic acid esters having a pKa of 3.5 or less. The compound of the formula (IV) is preferably selected from substituted aromatic carboxylic acid, alpha-hydroxycarboxylic acid and polycarboxylic acid esters.

According to one embodiment, the ester is a substituted aromatic carboxylic acid ester of the formula (IV) wherein R13 is a substituted aryl group. Preferably, R13 is a substituted aryl group having 6 to 10 carbon atoms, preferably a phenyl or naphthyl group, more preferably a phenyl group. R13 is advantageously substituted with one or more groups selected from carboalkoxy, nitro, cyano, hydroxy, SR₁₅ and NR₁₅R₁₆. Each of the R15 and R₁₆ group may be a hydrogen atom or an optionally substituted alkyl, alkenyl, aryl or carboalkoxy group. Each of the R₁₅ and R₁₆ groups advantageously represents a hydrogen atom or an optionally substituted C₁-22 alkyl group, preferably a hydrogen atom or C₁₋₁₆ alkyl group, more preferably a hydrogen atom or C₁₋₁₀ alkyl group, even more preferably a hydrogen atom or C₁₋₄ alkyl group. R₁₅ is preferably a hydrogen atom and R₁₆ is a hydrogen atom or a C₁ to C₄ group. Advantageously, R₁₅ and R₁₆ are both a hydrogen atom.

According to one embodiment, R13 is an aryl group substituted with one or more groups selected from hydroxyl, carboalkoxy, nitro, cyano and NH₂. R13 may be a polysubstituted aryl, for example trihydroxyphenyl, group. Advantageously, R13 is a monosubstituted aryl, preferably ortho-substituted, group. R13 is, for example, substituted with a group selected from OH, NH₂, NO₂ or COOMe, preferably OH or NH₂. R13 is preferably a hydroxy-aryl, in particular 2-hydroxyphenyl, group.

According to one particular embodiment, R14 is an alkyl or alkylaryl group. R14 may be a C₁ to C₁₆, preferably C₁ to C₁₀, advantageously C₁ to C₈, alkyl group. R14 may be a C₁ to C₁₆, preferably C₁ to C₁₀, advantageously C₁ to C₈, alkylaryl group. R14 may for example be selected from methyl, ethyl, propyl, butyl, pentyl, benzyl or isomers thereof. Preferably, R14 is a benzyl or methyl, more preferably methyl, group.

A particularly preferred compound is methyl salicylate.

According to one particular embodiment, the compound of the formula (IV) is an alpha-hydroxycarboxylic acid ester having the following formula (V):

wherein R17 and R18 are the same or different and are independently selected from the group consisting of a hydrogen atom, alkyl, alkenyl, awl or aralkyl groups. Such compounds are for example described in EP 1254889.

Examples of compounds of the formula (IV) wherein R13COO is the residue of an alpha-hydroxycarboxylic acid include methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, phenyl-, benzyl- or allyl-esters of 2-hydroxy-isobutyric acid; methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl- or allyl esters of 2-hydroxy-2-methylbutyric acid; methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl- or allyl esters of 2-hydroxy-2-ethylbutyric acid; methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl- or allyl-esters of lactic acid and methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, allyl-, benzyl- or phenyl-esters of glycolic acid. From the above, the preferred compound is methyl-2-hydroxyisobutyrate.

According to one particular embodiment, the compound of the formula (IV) is an ester of a polycarboxylic acid selected from dicarboxylic acids and carboxylic acids having more than two acid functions. The carboxylic functions are preferably all in esterified form. Preferred esters are C₁ to C₄ alkyl esters.

The compound of the formula (IV) may be selected from oxalic acid diesters, phthalic acid diesters, maleic acid diesters, malonic acid diesters or citric acid diesters. Preferably, the compound of the formula (IV) is dimethyl oxalate.

According to one preferred alternative, the compound of the formula (IV) is a carboxylic acid ester having a pKa of less than 3.5. In cases where the compound comprises more than one acid group, the first dissociation constant will be referred to.

The compound of formula (IV) may be selected from one or more carboxylic acid esters selected from oxalic acid, phthalic acid, salicylic acid, maleic acid, malonic acid, citric acid, nitrobenzoic acid, aminobenzoic acid and 2,4,6-trihydroxybenzoic acid. Preferred compounds of formula (IV) are dimethyl oxalate, methyl 2-nitrobenzoate and methyl salicylate.

According to one particularly preferred embodiment, the quaternary ammonium salt employed in the invention is formed by reaction of a hydrocarbon epoxide, preferably selected from those of formula (III) above and more preferably propylene oxide, with the reaction product of a polyisobutenyl succinic anhydride whose polyisobutylene (PIB) group has a number average molecular mass (Mn) of between 700 and 1000 and dimethylaminopropylamine.

According to one particularly preferred embodiment, the additive (1) is selected from polyisobutylene succinimides functionalised by a quaternary ammonium group.

The composition according to the invention comprises the first additive(s) as described above at a preferential content ranging from 5 to 10,000 ppm by weight, preferably from 5 to 1000 ppm by weight, more preferably from 10 to 500 ppm by weight, more preferably from 15 to 200 ppm by weight, and even more preferably from 20 to 150 ppm by weight, based on the total weight of the fuel composition.

The Second Additive: Polyisobutylene Succinimide

The composition according to the invention comprises a second additive (2) consisting of a non-quaternary polyisobutylene succinimide, i.e. it does not contain a quaternary ammonium group.

According to one preferred embodiment, said second additive results from the condensation:

-   -   of a compound A consisting of a carboxylic diacid substituted         with a polyisobutylene group or of an anhydride of such a         diacid,     -   with a compound B consisting of a primary polyamine of the         general formula (VI) hereinafter:

H₂N—[—(CHR1-(CH₂)_(p)—CHR₂)_(n)—NH]_(m)—H  (VI)

wherein R1 and R2, the same or different, represent hydrogen or a hydrocarbon group comprising from 1 to 4 carbon atoms, n is an integer ranging from 1 to 3, m is an integer ranging from 1 to 10, preferably from 1 to 4; and p is an integer equal to 0 or 1.

In one preferred embodiment, said additive (2) is obtained by condensation of compound A with compound B, used in such amounts that the A/B molar ratio is in the range from 1:1 to 1:3.

Preferably the molar ratio A/B is in the range from 1:1.1 to 1:2, even more preferably the molar ratio A/B is in the range from 1:1.1 to 1:1.5.

Said additive (2) may especially be obtained by condensation of 60 to 90% by weight of compound A, and 10 to 30% by weight of compound B.

The average molar mass of compounds A according to the present invention ranges from 200 to 3000, preferably from 200 to 2000 g/mol, more preferably from 200 to 1500 g/mol, even more preferably from 900 to 1300 g/mol. These compounds are well known in prior art.

Among the primary polyamines according to formula (VI), polyamines from the group consisting of diethylene triamine, dipropylene triamine, triethylene tetramine, tetraethylene pentamine and substituted derivatives thereof, or mixtures thereof, are preferred.

Mixing these compounds A and B may be carried out either in the order detailed below, or in a different order.

In one preferred embodiment, compound B, i.e. the primary polyamine of the formula (VI) is added to compound A, i.e. the carboxylic hydrocarbon(s) acid or anhydride(s).

Polyamine B is gradually added in an organic solvent and then to the solution of the carboxylic hydrocarbon mixture at room temperature, the mixture is then heated to between 65 and 250° C., and preferably between 80 and 220° C., for 5 to 30 hours.

The organic solvent required for solubilising the primary polyamine is selected with a boiling point between 65 and 250° C., and preferably between 80 and 220° C., and its ability to remove water formed by condensation of the polyamine on compound A by azeotropic distillation of the water/solvent mixture. The solvent is selected from the group consisting of benzene, toluene, xylenes, ethylbenzene and commercial hydrocarbon cuts, for example those distilling off from 190 to 209° C. and containing 99% by weight of aromatic compounds.

According to another embodiment of the invention, a mixture of solvents may be used, especially a mixture of xylenes, or a xylene/alcohol mixture, preferably the alcohol is 2-ethylhexanol, in order, on the one hand, to facilitate homogeneity of the medium and, on the other hand, to promote kinetics of the reaction.

After the end of the addition of the primary polyamine B, heating is maintained under reflux until the water is completely removed, for 0.5 to 7 hours, preferably 1 to 5 hours.

In one embodiment, the composition according to the invention comprises the second additive(s) as described above at a preferred content ranging from 5 to 10,000 ppm by weight, preferably from 5 to 1000 ppm by weight, more preferably from 10 to 500 ppm by weight, more preferably from 15 to 200 ppm by weight, and most preferably from 20 to 150 ppm by weight, based on the total weight of the fuel composition.

The Third Additive: Mannich Base

The fuel composition according to the invention comprises a third additive (3), different from the additives (1) and (2), consisting of a Mannich base. The preparation of Mannich bases is known per se, and for example described in documents US2008/0052985, or U.S. Pat. No. 8,016,898.

Advantageously, the third additive is prepared by reacting a hydrocarbon-substituted phenol, an aldehyde and an amine.

The hydrocarbon substituent of said phenol may contain from 6 to 400 carbon atoms, advantageously from 30 to 180 carbon atoms, preferably from 10 to 110, more preferably from 40 to 110 carbon atoms.

The hydrocarbon substituent of said phenol may be derived from an olefin or a polyolefin. By way of example, mention can be made of alpha-olefins such as n-1-decene. Preferably, the hydrocarbon substituent of said phenol is a polyisobutylene group.

The polyolefins forming the hydrocarbon substituent of the phenol may be prepared by polymerisation of olefin monomers according to any known polymerisation process.

Advantageously, the polyolefins are selected from polyisobutylenes having a number average molar mass (Mn) of between 400 and 3000, preferably between 400 and 2500, more preferably between 400 and 1500, between 500 and 1500 or between 500 and 1000.

Polyisobutylene is preferably highly reactive, which differs from low-reactive polyisobutylenes by their low amount of end ethylene double bonds. The reactive polyisobutylenes according to the invention, are composed of at least 85 wt. %, preferably at least 90 wt. %, most preferably at least 95 wt. % of isobutene units.

Preferably, the polyisobutylenes, which are preferably highly reactive, have a polydispersity of less than 1.9, preferably less than 1.7 and even more preferably less than 1.5, the polydispersity being the quotient of the weight-average molar mass Mw to the number-average molar mass Mn.

The hydrocarbon-substituted phenol can be prepared by alkylating phenol with an olefin or polyolefin described above, such as polyisobutylene or polypropylene, preferably polyisobutylene, using conventional alkylation methods.

According to one alternative, the phenol may be substituted with one or more low molecular weight alkyl groups, for example a phenol bearing one or more alkyl chains of less than 28 carbon atoms, preferably of less than 24 carbon atoms, more preferably of less than 20 carbon atoms, even more preferably of less than 18 carbon atoms, even more preferably of 16 carbon atoms and even more preferably of 14 carbon atoms.

A monoalkyl phenol having from 4 to 20 carbon atoms, preferably from 6 to 18, more preferably from 8 to 16, still more preferably from 10 to 14 carbon atoms, for example a phenol substituted with a C12 alkyl group, will be preferred.

The aldehyde used to form the Mannich reaction product may comprise from 1 to 10 carbon atoms, and is generally formaldehyde or its reactive equivalents such as formalin (methyl alcohol and formaldehyde), trioxanes, or para-formaldehyde, and preferably para-formaldehyde.

The amine used to form the Mannich reaction product may be a monoamine or a polyamine.

By way of non-limiting examples of monoamines, mention can be made of ethylamine, dimethylamine, diethylamine, di-n-propylamine, di-isopropylamine, n-butylamine, dibutylamine, allylamine, isobutylamine, cocoamine, stearylamine, laurylamine, methyllaurylamine, oleylamine, N-methyl-octylamine, dodecylamine, diethanolamine, morpholine, dimethylmorpholine, dicyclohexylamine, pyrrolidine, piperidine, diethylenetriamine, triethylenetetramine, N,N-diethylethylenediamine, N,N,N′,N′-tetramethyldiethylenetriamine, polyethyleneimines and octadecylamine. Polyamines are selected from compounds comprising two or more amino groups.

By way of non-limiting examples, mention can be made of polyalkylene polyamines in which the alkylene group has, for example, from 1 to 6, preferably from 1 to 4, more preferably from 2 to 3 carbon atoms. Preferred polyamines are polyethylene polyamines. The polyamine may comprise from 2 to 15 nitrogen atoms, preferably from 2 to 10 nitrogen atoms, more preferably from 2 to 8 nitrogen atoms. Examples of polyamines are: 3-(dimethylamino)-n-propylamine, di[3-(dimethylamino)-n-propyl]amine, di[3-(diethylamino)-n-propyl]amine, di[2-(dimethylamino)ethyl]amine, N-methylpiperazine.

According to one alternative, the amine used to form the Mannich reaction product comprises a diamine, preferably comprising a primary or secondary amine function involved in the Mannich reaction and a tertiary amine function.

According to another alternative, the additive (3) may be obtained by a Mannich reaction and then subjected to a reaction for obtaining a tertiary amine function; for example, a process using an intermediate compound comprising a secondary amine and obtained by Mannich reaction, which is then modified by, for example, alkylation to lead to a tertiary amine.

According to one embodiment, the content of the additive (3) ranges from 5 to 10,000 ppm by weight, preferably from 5 to 1000 ppm by weight, more preferably from 50 to 500 ppm by weight, more preferably from 100 to 500 ppm by weight, and most preferably from 150 to 450 ppm by weight, based on the total weight of the fuel composition.

Fuel Concentrate

Another object of the present invention is the use, in order to improve detergency properties of a gasoline fuel, of a fuel concentrate comprising at least the additives (1), (2) and (3), as defined above, in mixture with an organic liquid, said organic liquid being inert with respect to the first, second and third additive, and miscible with said fuel.

The organic liquid is advantageously miscible with liquid fuels, especially those from one or more sources selected from the group consisting of mineral, preferably petroleum, animal, vegetable and synthetic sources. By miscible, it is meant that the additives and the organic liquid form a solution or dispersion so as to facilitate mixing of the additives according to the invention in liquid fuels according to conventional fuel additivation processes.

The organic liquid is preferably selected from aromatic hydrocarbon solvents such as the solvent marketed under the name “SOLVESSO”, alcohols, ethers and other oxygenated compounds, and paraffin solvents such as hexane, pentane or isoparaffins, alone or in mixture.

The Fuel

The fuel according to the present invention contains a base from one or more sources selected from the group consisting of mineral, animal, vegetable and synthetic sources, and is preferably selected from hydrocarbon fuels, non-essentially hydrocarbon fuels and mixtures thereof.

Preferably, petroleum will be selected as the mineral source.

The fuel is advantageously selected from hydrocarbon fuels and non-essentially hydrocarbon fuels, alone or in mixture.

By hydrocarbon fuel, it is meant a fuel consisting of one or more compounds consisting solely of carbon and hydrogen. Gasolines are hydrocarbon fuels.

By non-essentially hydrocarbon fuel, it is meant a fuel consisting of one or more compounds which not essentially consist of carbon and hydrogen, i.e. which also contain other atoms, in particular oxygen atoms.

Hydrocarbon fuels include especially light distillates having a boiling point in the gasoline range, preferably between 30 and 210° C.

These light distillates may, for example, be selected from distillates obtained by direct distillation of crude hydrocarbons, vacuum distillates, hydrotreated distillates, distillates resulting from catalytic cracking and/or hydrocracking of vacuum distillates, distillates resulting from ARDS (atmospheric residue desulphurisation)-type conversion processes.

In other words, the hydrocarbon fuel is selected from among gasolines.

Gasolines include, in particular, all commercially available spark-ignition engine fuel compositions. As a representative example, gasolines complying with the NF EN 228 standard may be mentioned. Gasolines generally have sufficiently high octane numbers to avoid the pinking phenomenon. Typically, gasoline type fuels marketed in Europe, in accordance with the NF EN 228 standard, have a Motor Octane Number (MON) of over 85 and a Research Octane Number (RON) of at least 95. Gasoline-type fuels generally have a RON ranging from 90 to 100 and a MON ranging from 80 to 90, with RON and MON measured according to standard ASTM D 2699-86 or D 2700-86.

Non-essentially hydrocarbon fuels comprise especially oxygenates, e.g. distillates resulting from BTL (biomass to liquid) conversion of plant and/or animal biomass, alone or in combination; biofuels, e.g. oils and/or esters of plant and/or animal oils; and bioethanols.

Mixtures of hydrocarbon fuel and non-essentially hydrocarbon fuel are typically Ex-type gasolines.

By Ex-type gasoline for spark ignition engines, it is meant a gasoline fuel that contains x % (v/v) oxygenates, typically ethanol, bioethanol and/or ethyl-tertio-butyl-ether (ETBE).

The fuel composition may comprise only new distillate sources or may be comprised of a mixture with lighter conventional petroleum distillates as a gasoline-type fuel base.

Preferably, the content of each additive (1) and (2) in the fuel composition according to the invention ranges from 5 to 10,000 ppm by weight, preferably from 5 to 1000 ppm by weight, more preferably from 10 to 500 ppm by weight, more preferably from 15 to 200 ppm by weight, and most preferably from 20 to 150 ppm by weight, based on the total weight of the fuel composition.

Preferably, the content of the additive (3) in the fuel composition according to the invention ranges from 5 to 10,000 ppm by weight, preferably from 5 to 1000 ppm by weight, more preferably from 50 to 500 ppm by weight, more preferably from 100 to 500 ppm by weight, and most preferably from 150 to 450 ppm by weight, based on the total weight of the fuel composition.

Preferably, the sulphur content in the fuel composition is less than or equal to 1500 ppm by weight, preferably less than or equal to 1000 ppm by weight, preferably less than or equal to 500 ppm by weight and preferentially less than or equal to 50 ppm by weight, even more preferably less than or equal to 10 ppm by weight, based on the total weight of the composition, and advantageously sulphur-free.

Other Fuel Composition Additives

The fuel composition may also comprise one or more additional additive(s), different from said additives according to the invention.

This (these) additional additive or additives may, for example, be selected, in a non-limiting manner, from: detergent additives, anti-corrosion agents, anti-oxidants, carrier oils, dispersants, demulsifiers, tracers or markers, reodorants, friction modifiers, lubricating additives or lubricity additives, combustion aids (catalytic combustion and soot promoters), anti-settling agents, anti-wear agents and conductivity modifiers.

These additional additive(s) are more preferably selected from:

(a) lubricity additives or anti-wear agents, especially (but not limited to) selected from the group consisting of fatty acids and their ester or amide derivatives, especially glycerol monooleate, and mono- and polycyclic carboxylic acid derivatives. Examples of such additives are given in the following documents: EP680506, EP860494, W098/04656, EP915944, FR2772783, FR2772784;

b) detergent additives especially (but not exclusively) selected from polyetheramines;

c) friction or rubbing modifiers especially (but not limited to) selected from the group consisting of fatty acid or fatty acid esters or mixtures of fatty acid or fatty acid esters, for example oleic, linoleic, resinic, palmitic acids; or from fatty acid dimers, or mono- or di-propoxylated esters; sorbitan esters; sucrose stearates; or from glycerol and its derivatives; or pentaerythritol esters; or amines; and preferably selected from glycerol or polyglycerol esters, or fatty acid or esters, or mixtures thereof;

d) anti-corrosion additives especially (but not exclusively) selected from the group consisting of fatty acid or fatty acid esters or mixtures of fatty acid or fatty acid esters, or from fatty acid dimers;

e) antioxidants especially (but not limited to) selected from the group consisting of 2,6-di-t-butyl-4-methyl phenol, t-butyl hydroquinone, 2,6 and 2,4 di-t-butyl phenol, 2,4-dimethyl-6-t-butyl phenol, pyrogallol, tocopherol, 4,4′-methylene bis (2,6-di-t-butyl phenol), alone or in mixture;

f) carrier oils especially (but not exclusively) selected from the group consisting of polyoxyalkylenes such as, for example, poly-1-butene oxide or polypropene oxide.

These additional additives may be present in amounts ranging from 3 to 1000 ppm (each) by weight, based on the total weight of the fuel composition, preferably from 5 to 500 ppm.

Uses

A further object of the invention is the use of the fuel composition for keeping clean (keep-clean effect) and/or cleaning up (clean-up effect) deposits in the internal parts of an engine selected from the following: the combustion chamber and fuel injection system, and preferably the fuel injection system.

The composition according to the invention is effective in conventional engines; or more modern engines such as, GDI, BMW B48, Renault HSFT and HR13DDT, PSA EB2DTS, Volkswagen EA111 etc.; and in IIE Mercedes M102E and M111E, PSA EW10A and EB2 etc.

Another object of the invention is the use of the fuel composition comprising at least one first additive, at least one second additive and at least one third additive defined above to prevent and/or reduce coking (i.e. coke deposits), especially in gasoline direct injection (GDI), and/or lacquering (i.e. deposits of soaps and/or lacquers) especially in gasoline indirect injection (GII), and especially on the valves.

The invention thus makes it possible to prevent and/or reduce coke and/or soap deposits on the fuel intake valves in a indirect injection spark ignition engine.

Another object of the invention is the use of the fuel composition comprising at least one first additive, at least one second additive and at least one third additive defined above to prevent and/or reduce sticking (or valve-sticking) of the fuel intake valves in an engine, especially a gasoline indirect injection (GII) spark ignition engine. In this embodiment, said composition advantageously further comprises a fourth additive which is a carrier oil.

In the case of the use to combat valve-sticking, the composition preferably further comprises a carrier oil. The carrier oil may be selected from poly(oxyalkylene) type oils, for example poly-1-butene oxide or poly-propene oxide. In one embodiment, the weight ratio of the amount of carrier oil to the amount of detergent additives is in the range from 0.1 to 2.5, preferably from 0.3 to 1.5, even more preferably from 0.5 to 1.

Another object of the invention is the use of said fuel composition to reduce fuel consumption of the engine (“Fuel Eco” action) and/or to minimise power loss of said engine, and/or to reduce pollutant emissions, in particular, particulate emissions of the combustion engine.

Another object of the invention is the use of said additive composition to reduce fouling of the zone of the pistons, rings, and liners of the engine, preferably of a gasoline direct injection (or GDI) engine.

The quaternary ammonium additive (1), as defined in the present invention, is particularly effective in combating piston fouling, especially in GDI.

The combination of additives (1) and (2) is also very effective in combating piston fouling, especially in GDI.

The fuel composition can be used in gasoline indirect injection (GII) or gasoline direct injection (GDI), preferably in GDI. In one embodiment, the GDI is central-mounted, and in another embodiment, the GDI is side-mounted. The present invention is therefore effective and used in central- and/or side-mounted GDI.

The fuel composition can also be used to combat corrosion in the engine. The additive (2) polyisobutylene succinimide, as defined in the present invention, is particularly effective in combating corrosion.

The use according to the invention is applicable to engines used in light vehicles (LV), heavy goods vehicles (HGV), stationary machines, agricultural machines, thermal vehicles or hybrid (rechargeable or not) vehicles, gasoline/gas bi-fuel engines, for example gasoline/NGV (Natural Gas for Vehicles) or gasoline/LPG; gasoline/NGV or gasoline/LPG concomitant injection engines, etc.

The additive composition, fuel or concentrate can be used in “severe” or “easier to treat” gasolines. “Severe” gasolines are distinguished from “easy-to-treat” gasolines in that a severe gasoline requires a higher additive composition treatment rate to be effective than an “easy-to-treat” gasoline. Gasolines similar to the reference gasolines CEC RF12-09 and CEC RF-83 can be mentioned as “severe” gasolines.

Process (or Method) for Preparing the Fuel Composition

The fuel composition according to the invention may be prepared according to any known process, by additivating a liquid hydrocarbon cut as described above with at least the three additives as described above, and optionally one or more other additives different from the additives according to the invention, as previously described.

Process for Improving Engine Cleanliness

The invention also relates to a process for keeping clean and/or cleaning up at least one of the internal parts of a spark ignition engine, comprising at least the following steps:

-   -   preparing a fuel composition by additivating a fuel with at         least the three additives as described above or with a         concentrate comprising them, then     -   combusting said fuel composition in said spark ignition engine.

All characteristics of the additives, the fuel or the use are applicable to the process.

According to one alternative, the step of preparing the fuel composition hereinabove is preceded by a preliminary step of determining the content of each of the three additives to be incorporated into said fuel composition to achieve a given specification relating to the detergency properties of the fuel composition.

This preliminary step is common practice in the field of fuel additivation and involves defining at least one characteristic representative of detergency properties of the fuel composition as well as a target value.

Methods for evaluating the detergency properties of fuels have been widely described in the literature and are within the general knowledge of the skilled person. As a non-limiting example, the following standardised or professionally recognised tests or methods described in the literature can be cited for indirect injection spark ignition engines:

-   -   Mercedes Benz method M102E, standard test method CEC F-05-A-93,         and     -   Mercedes Benz method M111E, Standard Test method CEC F-20-A-98.

These methods make it possible to measure intake valve deposits (IVD), with tests typically performed on Eurosuper gasoline meeting standard EN228.

For direct injection spark ignition engines:

-   -   the method described by the applicant in the paper “Evaluating         Injector Fouling in Direct Injection Spark Ignition Engines”,         Mathieu Arondel, Philippe China, Julien Gueit; Conventional and         future energy for automobiles; 10th international colloquium;         Jan. 20-22, 2015, p. 375-386 (Technische Akademie Esslingen by         Techn. Akad. Esslingen, Ostfildern), for the evaluation of         coking type deposits on the injector,     -   the method described in US20130104826, for the evaluation of         coking type deposits on the injector,     -   the method VW EA111 being developed within the framework of CEC         TDG-F-113 based on the VW EA111 engine (Glawar, A., et al.,         “Development of a Fuel System Cleanliness Test Method in a Euro         4 Direct-Injection Gasoline Engine (VW 1.4 L TSI 90 kW),” SAE         Int. J. Fuels Lubr. 10(3):2017, doi: 10.4271/2017-01-2296).

The method CEC L111-16 for evaluating fouling of the zone of pistons, rings, and liners of a gasoline direct injection engine can also be cited.

The following examples are given in order to illustrate the invention and should not be construed as limiting the scope thereof.

Examples

The examples hereinafter are based on a gasoline E, the characteristics of which are detailed in Table 1 below.

TABLE 1 characteristics of gasoline E Characteristics Method Value Density at 15° C. ISO 12185 748.3 kg/m³ Distillation profile ISO 3405 Initial point 36.2° C. 5% vol. point 51.2° C. 10% vol. point 54.6° C. 20% vol. point 59.6° C. 30% vol. point 63.9° C. 40% vol. point 68.0° C. 50% vol. point 92.1° C. 60% vol. point 102.2° C. 70% vol. point 109.2° C. 80% vol. point 116.5° C. 90% vol. point 138.1° C. 95% vol. point 163.5° C. Final point 183.5° C. E70 (% distilled 42.5% by at 70° C.) volume E100 (% distilled 55.5% by at 100° C.) volume E150 (% distilled 92.3% by at 150° C.) volume Sulphur content ISO 20846 8.8 mg/kg Existent gum content ISO 6246 <0.5 mg/100 mL Existent gum content <0.5 mg/100 mL Research octane number ISO 5164 96.2 Motor octane number ISO 5163 86.2 Oxidation stability ISO 7536 >360 min Composition by GC ASTM D6730 n-paraffins 6.12% by weight Iso-paraffins 32.16% by weight Naphthens 8.09% by weight Aromatics 33.63% by weight Olefins 9.58% by weight Ethanol 10.01% by weight Other compounds 0.41% by weight Carbon content ASTM D5291 85.5% by weight Hydrogen content ASTM D5291 13.7% by weight Net calorific value calculated ASTM D240 41.955 MJ/kg Water content ISO 12937 260 mg/kg Equivalent vapour pressure REID EN 13016-1 55.6 kPa DVPE Total oxygen content M0238LA2008 0.5% by weight

Fuel compositions have been prepared by adding the following additives A1, A2 and A3 to gasoline G:

-   -   A1: quaternary ammonium salt, formed by reacting propylene oxide         with the condensation product of a polyisobutenyl succinic         anhydride whose polyisobutylene (PM) group has a number average         molecular weight (Mn) of 1000 g/mol and dimethyl         aminopropylamine;     -   A2: polyisobutylene succinimide, obtained by condensation of a         polyisobutenyl succinic anhydride whose polyisobutylene group         (PIB) has a number average molecular mass (Mn) of 1000 g/mol and         tetraethylenepentamine;     -   A3: Mannich base, obtained by reacting a polyisobutylene (PIB)         group-substituted phenol having a number average molecular         weight (Mn) of 1000 g/mol, with formaldehyde and         dimethylaminopropylamine.

The amount of additive added to each composition is detailed in Table 2 below, wherein the content of each additive is given in ppm by weight based on the total weight of the final composition:

TABLE 2 Fuel compositions from gasoline G Additives Composition Composition Composition Composition added G1 G2 G3 G4 A1 50 120 0 0 A2 70 0 120 0 A3 313 313 313 313

Composition G1 is in accordance with the invention. The compositions G2, G3 and G4 are comparative. The additivation rate is identical for all three compositions G1, G2 and G3 (433 ppm).

The detergency performance of each of the above fuel compositions G1 to G4 as well as the non-additivated reference fuel G has been evaluated using a test for determining the fouling level of the injectors of a gasoline direct injection (GDI) engine.

The engine used is a PSA EB2DTS engine, which is a 3-cylinder 1199 cm³ turbocharged direct injection gasoline engine with centrally located injectors.

Before the test is carried out, the injector flow rate is determined using an EFS IFR 600 type injector flow meter testing machine, which makes it possible in a known manner per se to measure the fuel mass flow rate of the injectors.

The principle of the test is to run the engine for 5 hours at 4300 rpm and 11 bar mean effective pressure (hereinafter referred to as MEP), feeding it with the gasoline tested at an injection pressure of 70 bar, after a warm-up period of 20 minutes and a stabilisation period of 10 minutes.

The test is used to determine the average loss of flow rate, defined as corresponding to the average restriction in the flow of gasoline from the engine injectors at the end of the test. The higher the average loss of flow rate, the more fouling effect the fuel has on the engine injectors and the poorer its detergent performance.

The steps of the test are as follows:

-   -   A heating step;     -   A stabilisation step;     -   A fouling step;     -   A step of determining the injector loss of flow rate.

The test conditions are as follows:

Temperatures:

-   -   Water at engine outlet: 90±2° C.     -   Oil: 110±5° C.     -   Air in the intake manifold: 40±2° C.     -   Fuel in low pressure loop: 50±2° C.     -   Fuel injection pressure: 70 bar

For the warm-up phase, the engine is subjected to a progressive increase in speed, for a period of 20 minutes, until it reaches a speed of 4000 rpm and a MEP of 8 bar.

For the stabilisation phase, the engine is kept at the operating conditions of the test, at a speed of 4300 rpm, at a MEP of 11 bar and a fuel injection pressure of 70 bar, for a period of 10 minutes.

For the fouling phase, the engine is then run for 5 hours at 4300 rpm and 11 bar MEP with a fuel injection pressure of 70 bar.

At the end of the test, the injectors are removed for evaluation using the EFS IFR 600 injector flow meter testing machine, which measures the fuel mass flow rate of the injectors at the end of the test. The injector average loss of flow rate is calculated by comparison with the injector mass fuel flow rate value measured before the test.

The results obtained are detailed in Table 3 below.

TABLE 3 Results Composition G1 G2 G3 G4 G Average loss of flow rate 5.2% 6.7% 14.3% 16.2% 17.5%

The results above show that the composition G1 according to the invention containing the combination of the three additives A1, A2 and A3 leads to very good results in terms of reduction in the fouling of the injectors (“keep clean” effect). With the same total additive content (433 ppm), these results are significantly better than those obtained with the comparative compositions G2 and G3 containing only two of the three additives. The results obtained with the composition G4 containing only one of the three additives, and with the reference fuel G, are even worse.

These results illustrate the synergistic effects provided by the combination of the two additives according to the present invention. 

1. A use, for reducing and/or preventing deposits along internal parts of a spark ignition engine, of a fuel composition comprising: (1) at least one first additive consisting of a quaternary ammonium salt, (2) at least one second additive consisting of a non-quaternary polyisobutylene succinimide, (3) at least one third additive different from the additives (1) and (2), consisting of a Mannich base, and wherein the mass ratio of the amount of the first additive to the amount of the second additive is in the range from 0.2:1 to 2.5:1.
 2. The use according to claim 1, wherein the mass ratio of the amount of the first additive to the amount of the second additive is in the range from 1:1 to 2:1.
 3. The use according to claim 1, wherein the first additive (1) consisting of quaternary ammonium salt is obtained by reacting, with a quaternisation agent, a nitrogen compound comprising a tertiary amine function, this compound being the product of the reaction of an acylating agent substituted with a hydrocarbon group and a compound comprising at least one tertiary amine group and at least one group selected from primary amines, secondary amines and alcohols.
 4. The use according to claim 3, wherein the acylating agent substituted with a hydrocarbon group is selected from mono- or poly-carboxylic acids and derivatives thereof.
 5. The use according to claim 3, wherein the acylating agent substituted with a hydrocarbon group is a polyisobutenyl succinic anhydride.
 6. The use according to claim 3, wherein the compound comprising at least one tertiary amine group and at least one group selected from primary amines, secondary amines and alcohols is selected from amines of following formula (I) or (II):

wherein: R6 and R7 are identical or different and represent, independently of each other, an alkyl group having from 1 to 22 carbon atoms; X is an alkylene group having from 1 to 20 carbon atoms; m is an integer between 1 and 5; n is an integer from 0 to 20; and R8 is a hydrogen atom or a C₁-C₂₂ alkyl group.
 7. The use according to claim 3, wherein the quaternisation agent is selected from the group consisting of dialkyl sulphates, carboxylic acid esters; alkyl halides, benzyl halides, hydrocarbon carbonates, and hydrocarbon epoxides optionally in mixture with an acid, alone or in mixture.
 8. The use according to claim 1, wherein the additive (1) is selected from polyisobutylene succinimides functionalised with a quaternary ammonium group.
 9. The use according to claim 1, wherein the additive (2) consisting of a non-quaternary polyisobutylene succinimide results from the condensation: of a compound A consisting of a carboxylic diacid substituted with a polyisobutylene group or of an anhydride of such a diacid; with a compound B consisting of a primary polyamine of general formula (VI) hereafter: H₂N—[—(CHR1-(CH₂)_(p)—CHR₂)_(n)—NH]_(m)—H  (VI) wherein R1 and R2, which are identical or different, represent hydrogen or a hydrocarbon group comprising from 1 to 4 carbon atoms, n is an integer ranging from 1 to 3, m is an integer ranging from 1 to 10; and p is an integer equal to 0 or
 1. 10. The use according to claim 9, wherein said additive (2) is obtained by condensation of compound A with compound B used in such amounts that the molar ratio A/B is in the range from 1:1 to 1:3.
 11. The use according to claim 1, wherein the additive (3) consisting of a Mannich base is obtained by reacting a phenol substituted with a hydrocarbon group, an aldehyde and an amine, the hydrocarbon substituent of said phenol comprising from 6 to 400 carbon atoms.
 12. The use according to claim 1, wherein the fuel contains a base from one or more sources selected from the group consisting of mineral, animal, vegetable and synthetic sources.
 13. The use according to claim 1, wherein the content of each additive (1) and (2) ranges from 5 to 10,000 ppm by weight, based on the total weight of the fuel composition.
 14. The use according to claim 1, wherein the content of the additive (3) ranges from 5 to 10,000 ppm by weight, based on the total weight of the fuel composition.
 15. (canceled)
 16. The use according to claim 1, where such use is for keeping clean (keep-clean effect) and/or cleaning up (clean-up effect) deposits in the internal parts of the spark ignition engine selected from the following: the combustion chamber and the fuel injection system.
 17. The use according to claim 1, where such use is for preventing and/or reducing coke and/or soap deposits on the fuel intake valves in the spark ignition engine, the spark ignition engine being an indirect injection spark ignition engine.
 18. The use according to claim 1, where such use is for preventing and/or reducing valve-sticking of fuel intake valves in the spark ignition engine, the spark ignition engine being an indirect injection spark ignition engine.
 19. The use according to claim 1, wherein the additive composition is used in the fuel to reduce fuel consumption of the engine (“Fuel Eco” action) and/or minimise power loss of said engine, and/or reduce pollutant emissions.
 20. (canceled)
 21. A use, for improving detergency properties of a gasoline fuel, of a fuel concentrate comprising at least the additives (1), (2) and (3), as defined in claim 1, in mixture with an organic liquid, said organic liquid being inert towards the first, second and third additive, and miscible with said fuel.
 22. A process for keeping clean and/or cleaning up at least one of the internal parts of a spark ignition engine or gasoline internal combustion engine, comprising at least the following steps: preparing a fuel composition by additivating a fuel with at least the additives (1), (2) and (3), as defined in claim 1, and then combusting said fuel composition in said spark ignition engine. 